Note that all the manufacturers aren't actually saying the URE is X. They are saying it's less than X, it's a cap. Therefore it isn't a rate. The actual rate for two drives could be very different, maybe even more than an order of magnitude different, but so long as it's below the spec's cap for such errors, it's considered normal operation.

So yeah, I agree, the whole idea in some circles that you will get a URE every ~12TB of data read is obviously b.s. We don't know what the real world rate is because of that little less than sign that appears in all of these specs. We only know there won't be more errors than that, and not for a specific drive, but rather across a (virtual) sample size for that make/model of drive.